Tens of thousands of travellers have had their travel plans wrecked by the first French air-traffic control strike of the year.
Many controllers stopped work on Wednesday night in support of a national strike against labour reforms and to seek better resourcing during busy periods.
The air-traffic walk-out is due to end on Friday morning, which is when a separate strike by Air France staff begins.
The French authorities have ordered airlines flying to, from or over France on Thursday to cull around 30 per cent of their flights – though Air France has cancelled fewer, at around 20 per cent.
The French national carrier aims to operate all its long-haul flights, three-quarters of medium-haul flights to and from Paris Charles de Gaulle (CDG) and 60 per cent of short-haul flights to and from Paris Orly and the French provinces.
Some Air France flights to and from Paris CDG from Heathrow, Birmingham, Manchester and Edinburgh have been grounded.
The worst-affected areas are in western and southern France, at the control centres in Brest, Bordeaux and Marseilles.
Many flights from the UK to Spain and Portugal are severely disrupted. Some aircraft are using “Tango routes” that fly out over the Atlantic to avoid French airspace, but not all planes are suitably equipped.
The longer routes cause delays and consume more fuel.
The UK’s biggest budget airline, easyJet, has cancelled 110 flights, including 18 at its main base, Gatwick. Three round-trips to Barcelona have been grounded.
The airline said: “easyJet has advised those on affected flights in advance, allowing customers the time to make alternative travel arrangements.
“Affected customers will be able to transfer their flight free of charge or receive a refund and hotel accommodation and meals will be provided for passengers where required.
“Whilst this is outside of our control we would like to thank customers for their patience and apologise for any inconvenience experienced as a result of this industrial action.”
British Airways (BA) has cancelled more than 50 flights, mainly to France but also to airports in Spain and Switzerland. BA said: “Yet again this will unfortunately bring another wave of unnecessary disruption for some customers travelling in Europe.
“We will be using larger aircraft, where possible, to help affected customers and are doing all we can to reduce the levels of disruption.
“Public transport to and from airports could also be affected by the national strike, so please allow extra time for your travel plans before and after your flights.”
Ryanair has cancelled 30 flights to and from Stansted so far and is warning: “Further flight delays and cancellations are likely and customers are asked to please monitor this notice which will be updated throughout the day.”
Most of the affected departures are to Spain, with two round trips to and from Alicante, Barcelona and Malaga cancelled.
The airline said: “Ryanair sincerely apologises for any inconvenience caused by these unjustified ATC disruptions which are entirely outside of our control.”
Air France has already started cancelling UK flights ahead of Friday’s strike by airline staff. Ten flights connecting Heathrow and Manchester and Paris CDG have so far been cancelled.
Separately, Austrian Airlines staff are on strike, and 150 flights – including some services between Heathrow and Vienna – have been grounded.